$ mkdir ~/.cpan
$ mkdir ~/.cpan/CPAN
$ cd ~/.cpan/CPAN
$ cp /usr/lib/perl5/5.8.4/CPAN/Config.pm MyConfig.pm
$ perl -pi -e's!/root/\.cpan!$ENV{HOME}/.cpan!' MyConfig.pm
$ perl -pi -e'/makepl_arg/ && s!\]! PREFIX=$ENV{HOME}]!' MyConfig.pm
$ echo "export PERL5LIB=${HOME}/lib/perl5/site_perl/5.8.4/i686-linux:${HOME}/lib/perl5/site_perl/5.8.4" >> ~/.bash_profile
$ source ~/.bash_profile
$ cpan

cpan shell -- CPAN exploration and modules installation (v1.7601)
ReadLine support enabled

cpan>